engine and drivetrain tii running issues: Updated 2/27/2012

[jgerock]

See latest entry for updates.

Now that the 5 speed O.D. trans drops my speed by about 800 rpm, it puts the engine in the dreaded 2,250 - 2,600 rpm range where it bucks like crazy while holding a steady throttle at around 40 mph (was in 3rd, now in 4th).

I got tired of guessing my CO, so I installed an analog wideband sensor this weekend. AEM # 30-5130 was selected after discussing my needs with Marshall Lytle. With help from Bill Riblett, the NPT fitting was welded to my down-pipe yesterday.

I installed the Bosch sensor, then ran the cable up along the tranny and used an existing hole thru the pass. side.

The gauge is placed on the little shelf next to the instrument cluster. I haven't fully stuck the gauge base to the dash yet (velcro).

[jgerock]

At idle (1000 rpm) when fully warm, the gauge reads about 12. When you race the engine, the gauge pegs to 18, then returns to about 11.5 quickly after letting off the throttle.

When driving around, immediately after taking off from rest, the needle stays at 18.

If I lift off the pedal, the gauge will drop to around 15-16.

While driving, if I downshift and run the engine pretty hard, the gauge drops from 18 down to around 15.

At the dreaded 2,500 rpm/40mph/steady pressure on the gas pedal, the gauge reads about 16.

I just checked my KF linkages (again) and can confirm the warm-up regulator cone is extended about 10mm out of the housing fully-warmed up (water temp. needle about 1/2 way).

Another oddity is if I try to reduce the idle speed (when warmed up), backing off the grub screw will not move the cam to slow the engine. you have to physically push the cam forward.

[jgerock]

While idling

Holding the throttle (car not moving)

I need some professional tii help.

[gwb72tii]

are you dead nuts certain your linkage is spot on, especially the clearance of the "hat" on the warm-up regulator?

[jgerry2002]

Something does not sound right with the gauge setup. Is this a true wideband kit, as in both the gauge and the O2 sensor are wideband? Also is there any calibration? The innovate motorsports kits I've used need to be calibrated to air around it before you start taking readings.

The car leaning out like that does not make sense. You'd have very very little power. And if you were that lean (18!??!), you'd have lots of popping,cracking and the occasional backfire. Your plugs would be really really clean as well. What do your plugs look like?

At WOT you should be (ideally) ~12.5-13, idle Tii's seems to like about 12.9.-13.1. Cruise should be ~15.

Are all the linkages fresh and adjusted? How is the timing? Valve timing? Distributor working ok? How old are the distributor advance springs? Does the timing look advance look ok with a timing light? If all of that is 100%, THEN start playing with the mixture.

[jimk]

It will buck if the A/F ratio is at 18. Your gauge is most likely ok, the FI settings need help. I am an EFI guy, so you need to RTFM on the Tii FI.

[ray_]

I'm not sure your gauge is responding correctly. I also don't think 16 at 2500 under light load will cause bucking. Check your ignition :-)

The attached pic shows target afr's for an S14. The leftmost column is referring to throttle angles.

GL.

Cheers,

Ray

At idle (1000 rpm) when fully warm, the gauge reads about 12. When you race the engine, the gauge pegs to 18, then returns to about 11.5 quickly after letting off the throttle.

When driving around, immediately after taking off from rest, the needle stays at 18.

If I lift off the pedal, the gauge will drop to around 15-16.

While driving, if I downshift and run the engine pretty hard, the gauge drops from 18 down to around 15.

At the dreaded 2,500 rpm/40mph/steady pressure on the gas pedal, the gauge reads about 16.

I just checked my KF linkages (again) and can confirm the warm-up regulator cone is extended about 10mm out of the housing fully-warmed up (water temp. needle about 1/2 way).

Another oddity is if I try to reduce the idle speed (when warmed up), backing off the grub screw will not move the cam to slow the engine. you have to physically push the cam forward.

[Adamha]

An alternate theory;

You just finished the 5 speed install, are you sure that your shaft is aligned perfectly?

A buck at that RPM could indicate a shaft out of alignment if consistent at that RPM range in all gears.

Just had to solve the same problem on my Tii post 5 speed install. Just a tiny bit out of alignment and only showed itself at about that same RPM range (My "buck" was at about 2800 RPM).

[jgerock]

Thanks for the responses - I'll try to answer everything in one itemized list:

1) Two of the (3) linkages are brand new. All are the correct length and I've shimmed the pivot points with nylon washers to reduce any slop. KF pump is synchronized with throttle body. Idle and full throttle settings were just checked yesterday.

2) Distributor is the correct (for 73tii) Bosch # 0231 151 008 which was just rebuilt and recurved by Advanced Distributors in MN. Timing at idle is set for 10 degrees BTDC (between 10-14 degrees as recommended by the rebuilder).

2a) Using a new Bosch "002" remanufactured distributor did NOT make the bucking go away.

2b) I am running stock points, condensor, cap, rotor, wires, Bosch Super plugs and "Red" Coil with stock ballast resistor. (all parts with the exception of the ballast resistor have been replaced over the last year).

3) Valve clearances have been double-checked several times over the last year.

4) The bucking issue has been present even with the 4 speed trans.

5) The bucking issue was NOT present until after I had the KF pump rebuilt (Fairchild Industries in CA) and at the same time I installed a new head gasket and had the head surfaced. The head is now at minimum thickness. Pistons are 89.47mm (2nd oversize).

What I don't understand is that my fuel mileage is great, it doesn't smoke/backfire and has great power. Compression on a warm engine averages 180 PSI across the cylinders. Plugs look "normal" - maybe a little bit of black wetness # 4.

Is there any chance the tiny spring that keeps pressure on the butterfly valve (idle CO cam) is too weak??? This (to me) would then keep the idle speed too high.

[jgerock]

Ok - the engine is running too lean while accelerating.

This means that the little "verboten" screw on the KF pump needs to be screwed in (clockwise) to richen - CORRECT? I haven't touched the KF pump since it was rebuilt.

[ColinK]

The verboten screw will enrichen across the entire range.

Mark and note the adjustments so you can roll back.

is the cam stock? if not did Fairchild "match" the rebuild to the cam?

Another thing to try would be to take the car to reputable dyno shop and get some read outs. That would tell you if the AF ratios are correct of if the WB is misreading.

Good luck..

[jgerock]

Thanks Colin. My car has the stock camshaft, along with the intake and exhaust systems.

[BillWilliams]

Do you feel the bucking in your hands or butt?

All gears at that RPM?

Are you reporting AFR or %co?

If you are reporting 18 AFR, that would not even register on my AFR LED read out.

I am real rusty on this but I believe Stociometric, lambda 1, is:

14.7:1 AFR, or

14.28 %co, or

.4- .5 volts from the wideband sensor.

18 is real lean for our cars if my math is correct. Check my math please.

My yellow car likes 14.17 - 14.15 %co or 13.3 - 14.2:1 AFR

[gwb72tii]

one more time

have you checked thoroughly the operation of the warm up valve?

it is an Auxiliary air valve, and if it is not adjusted properly it will meter more air than required leaning out your air/fuel mixture.

http://2002tii.org/kb/120

this web site is full of tii info

you can also find the tii fuel injection manual/video

[JohnC]

There could be a clogged fuel filter or screen. Mine was bucking a bit on the freeway until I cleaned the screen at the bottom of the tank inlet, and the little screen at the fuel pump. A noisy fuel pump is also a symptom of clogged screens.